LCL / UCL (Lower and Upper Control Limits)
Lower Control Limits (LCL) and Upper Control Limits (UCL) mark the expected range of variation for a stable process. Data points outside the limits prompt investigation before defects proliferate.
Calculating control limits
Control limits are generally set at three standard deviations from the process mean. They differ from specification limits, which are dictated by customer requirements.
Interpreting signals
Patterns such as runs, trends, or cycles inside the control limits can also indicate instability. Teams use statistical rules to determine when to intervene.
Combining control charts with Cpk analysis ensures the process stays both stable and capable.
Visibility within KaizenQ
KaizenQ visualises measurement data over time, highlighting breaches of control limits and automatically notifying stakeholders to contain potential issues.
- Control limits separate common cause from special cause variation.
- Signals outside the limits warrant immediate investigation.
- KaizenQ alerts teams when data trends point toward instability.